Hitachi Relion 670 Series Applications Manual page 324

Section 22
Basic IED functions
the block "group name", the analog inputs type (voltage or current) and the analog input names can be
set directly in ACT.
Application functions should be connected to a SMAI block with same task cycle as the application
function, except for e.g. measurement functions that run in slow cycle tasks.
DFTRefExtOut: Parameter valid only for function block SMAI1 .
Reference block for external output (SPFCOUT function output).
DFTReference: Reference DFT for the SMAI block use.
These DFT reference block settings decide DFT reference for DFT calculations. The setting
InternalDFTRef will use fixed DFT reference based on set system frequency. DFTRefGrp(n) will use DFT
reference from the selected group block, when own group is selected, an adaptive DFT reference will be
used based on calculated signal frequency from own group. The setting ExternalDFTRef will use
reference based on what is connected to input DFTSPFC.
The setting ConnectionType: Connection type for that specific instance (n) of the SMAI (if it is Ph-N or
Ph-Ph). Depending on connection type setting the not connected Ph-N or Ph-Ph outputs will be
calculated as long as they are possible to calculate. E.g. at Ph-Ph connection A, B and C will be
calculated for use in symmetrical situations. If N component should be used respectively the phase
component during faults I
Negation: If the user wants to negate the 3ph signal, it is possible to choose to negate only the phase
signals Negate3Ph, only the neutral signal NegateN or both Negate3Ph+N. negation means rotation with
180° of the vectors.
GlobalBaseSel: Selects the global base value group used by the function to define (IBase), (VBase) and
(SBase).
MinValFreqMeas: The minimum value of the voltage for which the frequency is calculated, expressed as
percent of VBase (for each instance n).
Examples of adaptive frequency tracking
318
/V must be connected to input 4.
N N
Settings DFTRefExtOut and DFTReference shall be set to default value InternalDFTRef if no
VT inputs are available.
Even if the user sets the AnalogInputType of a SMAI block to "Current", the MinValFreqMeas
is still visible. However, using the current channel values as base for frequency measurement
is not recommendable for a number of reasons, not last among them being the low level of
currents that one can have in normal operating conditions.
Preprocessing block shall only be used to feed functions within the same execution cycles
(e.g. use preprocessing block with cycle 1 to feed transformer differential protection). The only
exceptions are measurement functions (CVMMXN, CMMXU,VMMXU, etc.) which shall be fed
by preprocessing blocks with cycle 8.
When two or more preprocessing blocks are used to feed one protection function (e.g. over-
power function GOPPDOP), it is of outmost importance that parameter setting DFTReference
has the same set value for all of the preprocessing blocks involved
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1MRK511407-UUS Rev. N
Phasor measurement unit RES670
Application manual